Breathing apparatus



Nov. 2, 1948. P. E. MEIDENBAUER, JR

BREATHING APPARATUS 8 Sheets-Sheet 1 Filed April 10, 1944 a I a uvsmg flf.

ATTORNEYS Nov. 2, 1948. P. E. MEIDENBAUER, JR 2,452,670

' BREATHING APPARATUS Filed April 10, 1944 8 Sheets-Sheet 2 3 Z2 "691. I 2; Zia:

I 1 J i l l i I l l A I I m4 6% INVENTOR ATTORNEYS 8 Sheets-Sheet 3 1NVENTOR M 6041. f, BY

ATTORNEYS Nov. 2, 1948. P. E. MEIDENBAUER, JR

BREATHING APPARATUS Filed April 10. 1944 Nov. 2, 1948. P. E. MEIDENBAUER, JR

BREATHING APPARATUS Filed April 10, 1944 8 Sheets-Sheet 5 ATTQRNEYS Nov. 2, 1948. P. EC. MEIDENBAUER, JR

BREATHING APPARATUS 8 Sheets-Sheet 6 Fild April 10, 1944 aufamafck' (yaZe--' 1 Beware HMTWMZ (glaze KNVENTOR ATTORNEY 8 Sheets-Sheet 7 INVENTOR ATTORNEYS Nov. 2, 1948. P. E. MEIDENBAUER, JR

I BREATHING APPARATUS Filed April 10, 1944 Nov. 2, 1948. P. E. MEIDENBAUE'R, JR 2,452,670

BREATHING AEPARATUS 7 Filed April 10. 1944 v v a Sheets-Sheet e 1 INVENTOR ATTORNEY S Patented Nov. 2, 1948 UNITED STATES PATENT OFFICE 2,452,670 namrnmc APPARATUS Phillip E. Meidenbauer, Jr., Lancaster, N. Y., as-

signor to Scott Aviation Corporation, Lancaster, N. Y., a corporation of New York Application April 10, 1944, Serial No. 530,262

27 Claims. (Cl. 128142) This invention relates to a breathing apparatus which in an elaborate form is more particularly designed for use by aviators at high altitudes, although the same is also useful at low levels, and which in a simpler form is particularly useful at ground level for therapeutic purposes, such as treating pulmonary edema caused by War gases.

One of the objects of this invention is to provide an apparatus for this purpose which will operate efllciently and reliably to supply aviators with oxygen when flying at high altitudes either when he is conscious and able to help himself or when he is unconscious and unable to assist himself and wholly dependent on automatic operation of the apparatus for sustaining life.

Another object of this invention is to so organize the breathing apparatus that the same can be used for administering oxygen, medicated or other gases to patients at ground level for various ailments.

In the accompanying drawings:

Fig. 1 is a fragmentary side elevation, partly in section, of a breathing apparatus embodying a form of this invention which is more particularly designed for use by aviators when flying at high altitudes.

Fig. 2 is a vertical section of the pressure regulator whereby the gas which is received at high pressure from a supply source is reduced in pressure preparatory to being delivered to a person.

Fig. 3 is a vertical transverse section, on an enlarged scale, taken on line 3-3, Fig. 1, and

showing the auxiliary oxygen supply valve open.

Fig. 4 is a vertical longitudinal section, taken on line 4-4, Fig, 3.

Fig. 5 is a fragmentary vertical longitudinal section, taken 'on line 5-5, Fig. 3.

Fig. 6 is a fragmentary vertical longitudinal section of the face mask and the exhalation valve mechanism associated therewith.

' Fig. '7 is a fragmentary vertical longitudinal section similar to Fig. 4 but showing the snap action toggle mechanism which operates the main control valve in a different position.

Figs. 8, 9 and10 are cards or diagrams indicating the cycle of operations of the apparatus at different altitudes. Fig. 11 is a side elevation of a simpler form of apparatus embodying the essential features of this invention which are more particularly adapted for therapeutic uses.

Figs. 12 and 13 are cards or diagrams showing the operation of the apparatus shown in Fig. 11

, under different conditions.

Fig. 14 is a vertical transverse section, on an enlarged scale, taken on line "-44,, Fig. 11.

Fig. 15 is a vertical longitudinal section, taken on line l5-l5, Fig. 14.

Fig. 16 is a fragmentary view similar to Fig. 15 but showing the snap-action toggle mechanism in a different position.

Fig. 17 is' a fragmentary vertical longitudinal section, on an enlarged scale, of the face mask shown in Fig. 11 and the inhaling valve mechanism associated therewith.

In the following description like reference numerals indicate corresponding parts in the several figures of the drawings.

The general organization of the apparatus shown in Figs. 1-10 comprises a pressure regulator, a control mechanism whereby the gas is permitted to flow to or cut ofi from the face mask of the person, and an exhalation valve mechanism which controls the escape of the spent gas from the mask to the outer atmosphere,

Although the pressure regulator may be variously constructed, the same is preferably substantially like that shown in abandoned United States patent application Serial No. 508,946 which is as follows:

Referring to Figs. 1 and 2, the numeral 20 represents the body of the pressure regulator having a high pressure chamber 2|, a lower pressure chamber 22 and a port or passage 23 leading from the high pressure chamber to the low pressure chamber and provided around its outlet within the lower pressure chamber with a valve seat 24. Oxygen under high pressure supplied from storage bottles or other source is delivered by a tube 25 and coupling sleeve 26 to the high pressure chamber. The lower pressure chamber is provided with an outlet 21 formed in a tubular neck 28 from which the gas .is delivered to the means which control the supply of this gas to the person to be served.

Within the low pressure chamber is arranged a valve 29 which is movable toward and from the seat 24 for closing and opening the port 23 and which is mounted on a'carrier having plates 30, 3| between which the valve is secured by one or more screws 32. A light balancing spring 33 interposed between the front side of the carrier and the regulator body serves to move the valve carrier rearwardly and assist the high pressure fluid in its closing effect on this valve.

In rear of the body is arranged a bellows diaphragm 34 having its inner end secured to the body while its outer end is connected with 'a head 35. The interior of this bellows and the low pressure chamber are connected by a passage 38 in the body and the bellows head and the valve carrier are connected by one or more screws 31 which latter are surrounded by spacing sleeves 28 interposed between the valve carrier and the bellows head.

The opening movement of the regulator valve 28 is effected by a-heavy spring 39 interposed between the outerside of the bellows head and a follower 40 and the strength of this spring can be adjusted by an adjusting screw 4| engaging with the outer side of the follower and mounted on a casing 42. The latter is secured to the valve body and encloses the bellows and associated parts and provided with an opening 43 so as to expose the exterior of the bellows to atmospheric pressure. Before admitting fluid pressure into the low pressure chamber 22 the regulating valve is held open by the heavy spring 39 and the bellows is contracted, as shown in Fig. 2.

Upon admitting fluid under high pressure into the high pressure chamber 2| the same flows from this pressure chamber through the port 23 into the lower pressure chamber 2| and through the passage 36 and into the bellows. 34. As the pressure in the bellows builds up theiatter ex-. pandsand pulls the regulatingvalve 29 rearwardly through the medium of the bellows head screw 31-. and valve carrier, whereby the regulating valve, is moved toward the seat 24 and the port 23'is'. reduced in eifective area, thereby reducing the ,flu'id pressure in the v.iow pressure chamber accordingly. When the pressure in the low pres-.

surechamber has reached a predetermined .limit' the valve 29 closes the port 23 completely andwhen the pressure in the low pressure chamber open the regulating valve so as to resume theflow of fluid from thehi'gh pressure chamber to the lowpressure chamber.

being served isshown in Figs. 1, 3, 4, Sand? and.

constructed as follows:

The numeral 44 represents the body of thefluid control mechanism which is preferably supported while in use by means of a clasp 45 mounted on the rear side of this body and detachably this groove. A string 493 is tied around that part of the diaphragm which has been drawn into the groove 49! by the rubber band 492, thereby firmly holding the diaphragm in place. In assembling these parts the diaphragm is first placed manually over the case and then the rubber band 492 snapped in place. Then the wrinkles are smoothed out. this operation being facilitated by the fact that the rubber band holds the diaphragm while the wrinkles are being slid outwardly beneath it. When the diaphragm is all smooth the string 493 is applied. In its lower part the side wall of the body containing the respiration chamber is provided with a fluid inlet 50 which is connected by a coupling tube it with the upper end of the outlet tube 28 of the pressure regulator for conducting fluid from the latter to the respiration chamber. The upper part of the bore of the coupling tube is comparatively large so as to form an inlet chamber 52 for an automatically controlled inlet valve mechanism and the lower part of this bore has the form of a small metered hole or orifice 53 whose. function is to prevent fluid surges in the passage which connects the pressure regulator with the respiration chamber. By meuntil the exactdiameter ofholegiving the best results has been ascertained and then this size tomatic valve follows: 7 s5 The numeral 54 represents a valve plate or again drops below normal due to withdrawal of, fluid therefrom, the resilience of the heavy control spring 39 causes the bellows. to contract and connected with the front part of a harness wornon the body of. the person using the apparatus so that it will be transported by and always avail-.. able for this person.

The body of the'control mechanism is constructed-to formthe'fixedrear wall 46 and the fixed" peripheral or side wall 41 of a main valve or res-' piraton chamber and the front wall 49 of this chamber is formed by a flexible diaphragm which extends acrossan opening in the front of the body and has its peripheral edge secured to the side wall of the body, as shown in Figs. 3 and 4,

of hole is adapted as standard equipment.

Thepassage connecting. the pressure regulator and therespirationchamber is controlled by aumechanism which is constructed as body-which is secured between thevalve tube 5i andfthe control body; in suchfl'r'nanner that the joints-between the same are leak tight. In its central} part this valve body or plate is provided Wlfl'ha guide opening 55 for a tiltable valve stem 56 which extends loosely through this guide opening, and aplurality of'valve'ports' 5l which are arranged; around this guide opening and are 5 adapted-to. be uncovered orcoveredfor placing the pressure regulator either in-communlcation with by means which include a tiltable valve 58 arranged in the valve chamber 52 and secured to fluid inletv 50 and the lower part'jof therespiration chamber 48 and the same is'yijeldingly pulled bearing at its lower end against an internal shoul-" so that this diaphragm wall can collapse rear- I wardlyor inwardly and, expand forwardly or out'-" wardly. Although this diaphragm may be'secured to the casing or body in variousways this ls preferably eflected as follows:

The numeral 4Sl represents an annular groove I formed onthe exterior of the rim on the front side of the body. The marginal or edge portion upwardlyand heldin its central position by a springia' preferably of-conical'helical form secured at its upper end to; this'valvie stem and der on the valvediskf54, as shownin Fig. 4. When the valve stem 56 is free-the spring 58 turns the same into its centralposition in which the valve 51 is-rocked into a position-in which its plane is arranged at right angles to the axis oi the valve disk 54 and engages the valve seat 6.0 on" the. underside oiEthis valve disk so as to cover the valve ports 51- and the guide opening 55 and thereby prevent the flow of fluid from the regulator to the respiration chamber. Upon tipping the valve stem 56, thecontrol valve 58 will be rocked. so that-a part thereof engaging with the on'the opposite side of-this axis will. move away from thisvalve seat. as shown in Fig.- 4, thereby uncovering the-ports 51 and guide opening 55 and permitting flow of fluid from the regulator into the respiration chamber.

Opening and closing of the fluid control valve 58 is effected automatically by means which are responsive to the admission of fluid into the respiration chamber through the inlet 50 in the lower part thereof and the discharge of fluid through the outlet 6| which is preferably arranged in the upper part of its side wall. In their preferred form these automatic control means include the diaphragm or wall as a pressure responsive-element and are constructed as follows:

Within the lower part of the respiration chamber is arranged a toggle mechanism which includes lower and upper toggle levers which are adapted to rock relative to each other about an axis arranged transversely of the respiration chamber and part of the means for actuating the control wave 58 by motion derived from the diaphragm 49. The lower toggle lever is substantially U-shaped and comprises two parallel toggle arms 52, 63 pivoted at their upper ends by means of horizontal pivot pins 64 on bearing lugs 65 which form part of a base 66 secured to the back or rear wall 46 of the control mechanism body, and a lower cross bar 6'! connecting the lower ends of these arms. Theupper toggle lever is also of substantially U-shape and comprises two toggle arms 68, 69 arranged between the arms of the upper toggle lever and having their lower ends pivoted by the same pins 64 to said bearing lugs 65 while the upper ends of the upper toggle arms are connected by an upper cross bar 1!). The numeral ll represents a snap-action spring which is arranged lengthwise between the arms of the toggle levers and connected at its lower and upper ends, respectively, with the lower and upper toggle bars 61, .10, as shown in Fig. 3. Upon turning the toggle levers so that a line connecting the points at which the ends of the snap-spring H are attached to the toggle cross bars 67, 10 passes from one side of the axis 64 of these levers to the other thereof, this spring will be increasingly stretched upon approaching this axis and then contract upon moving away from this axis and quickly complete the folding action of the toggle levers in that direction and then yieldingly hold the toggle levers in a folded position on whichever side of said axis the toggle levers come to rest. The rearward folding movement of the toglevers is limited by a stop 14 which also preferably has the form of a screw secured in a threaded opening in the rear wall 46 of the body but does not require adjustment, This last mentioned stop 14 is engaged by a stop arm 15 projecting upwardly from the arm 62 of the lower toggle lever above the axis 64 of the latter. On its rear side the lower toggle cross bar 61 is provided with a rearwardly projecting trip flnger or tappet 16 which is arranged in line with the valve stem 56. When the toggle levers are folded forwardly the trip finger 16 is moved forwardly away from the valve stem 56 and permits the spring 59 to close the valve 58 but when the toggle levers are folded inwardly this trip finger engages the valve stem 55 and tilts the same rearwardly so that the valve 58 is tilted into an open position, as shown in Fig. 4, and thereby permits fluid under pressure to flow from the pressure regulator into the respiration chamber. The turning movement of the toggle levers is preferably so adjusted that forward folding action is arrested when the line between the points at which the snap spring I! has reached the dead center or axis 64 of the toggle levers or has passed slightly forward of this center or axis, .but the rearward folding movement of these levers is much greater in order to secure a slow or delayed closing of the control valve 58 and a quick or snap-action opening of the same.

Motion for turning of the toggle levers for folding the same either forwardly or rearwardly is efl'ected mainly by expanding the diaphragm forwardly or contracting the same rearwardly in response to alternately admitting compressed fluid into the respiration chamber and exhausting the same therefrom. For this purpose the movement of the diaphragm is transmitted to thetoggle levers by means of a shifting leg 11 which has its front end connected with the central part of the diaphragm and its inner part pivotally connected by a pin 18 with a shifting arm I9 on the upper toggle cross bar 10 while the rear end of this leg terminates close to the rear wall 46 of the control body.

In Fig. 4 the diaphragm has completed its rearward or collapsing movement and expelled a batch of fluid from the respiration chamber through its outlet BI and the inlet valve 58 has been quickly opened to admit another batch of compressed fluid into this chamber. As the compressed fluid enters the respiration chamber the diaphragm is gradually moved forwardly and expanded by the fluid until this chamber has been filled'as much as desired and during the initial part of this filling operation the toggle levers are gradully unfolded from their rearmost position and the snap-spring H is increasingly strained until it is at least in line with or somewhat forwardly beyond the dead center 64 at which point the resilience of the snap-spring H completes the outward folding movement of the toggle levers and the expansion of the diaphragm and quickly closes the control valve 58 for arresting the further entrance of compressed fluid into the respiration chamber.

Rearward or collapsing movement of the diaphragm for expelling the fluid from the respiration chamber, while the inlet valve is closed, is effected by the suction or inhalation of the person being served while breathing when he is conscious, which suction is aided by expelling means which are strained as the diaphragm is expanded and subsequently assist in again collapsing the diaphragm. These expelling means preferably comprise an expelling spring which has its front end connected with a pin 8!. on the upper toggle lever while its rear end is connected with an adjusting screw 82 which works in a threaded opening in the rear body wall 46 and is held in place by a clamping screw nut 82 applied to this screw and engaging the outer side of this wall, as shown in Fig. 4. This expelling spring also serves to resist the expanding action of the diaphragm and cause pressure to be built up in the fluid in the respiration chamber for aiding in its delivery from this chamber, which pressure :an be adjusted by means of the adjusting screw From the outlet of the respiration chamber the gaseous fluid is delivered by a flexible or corrugated rubber hose 83 to a mask 84 applied to the face of the person being served which mask may be of any suitable construction and preferably constructed so as to cover the mouth and nostrils. as shown in Fig. 11. The connection between the hose and the outlet of the respiration chamber is preferably effected by securing the lower end of this hose around an outlet tube 89 which is formed on the side wall 41 around the outlet 8| and the upper end of this tube is secured around an inlet tube 88 which is fastened to the face mask within a fluid inlet opening 81 on the lower part of the mask, as shown in Fig. 6. During automatic operation of the control mechanism in the respiration chamber and also by inhalation of the person being served, when he is conscious, oxygen or other gaseous fluid is drawn from this chamber into the mask and during exhalation by this person the spent fluid is discharged to the outer. atmosphere by a discharge valve mechanism which includes the following:

Within the mask is arranged a discharge valve case having a tubular body 88 a fixed head 89 at the inner side of the body provided with a port 90 and an outwardly facing valve seat 9i, and an outer detachable head 9| I provided with ports 92 adjacent to the body 88. The detachable head and the body of the discharge valve case are secured to the inner side of the front part of the mask by screws 93 which also serve to fasten other parts to the mask as will later appear. The numeral 94 represents an exhalation or discharge valve which is arrangedwithin the inner part of the discharge valve casing and which preferably is made of metal and has the form of a disk and is movable into and out of engagement with the valve seat 90 for closing and opening the exhalation port 89. This exhalation valve is associated with control means whereby this valve will close when the person using the apparatus is inhaling fresh fluid but will open when exhaling spent fluid, the control means being so constructed that the effort required to open the valve will vary according to the ambient air pressure of the altitude at which the breathing apparatus is being used. The control means for this purpose shown in Fig. 6 are constructedas follows:

The numeral 95 represents the flexible bellows or corrugated body of an aneroid, 96 its outer head which is secured to the inner side of the outer head 9i of the valve casing and 91 the inner head which is secured to the inner end of this body and forms with the same and the outer head 96 a hermetically sealed box from which the air threaded end to the central part of the inner aneroid head 91. while its inner part engages slidingly with an opening in the central part of the exhalation valve and its inner end is provided with a, head I which engages with the inner side of the valve 94. A spring IOI surrounds the valve stem 99 and bears at its opposite ends against the inner side of the valve 94 while its outer end bears-against the inner aneroid head 91.

While flying at comparatively low altitudes the heads of the aneroid are in engagement and form a solid abutment with each other, as shown in Fig. 6 so that the exhalation valve 98 is moved outwardly into an open position and permits the exhalation to escape, during which time the opening of this valve is only opposed by the spring II" which at this time exerts the least resistance to the opening of this valve. When flying at medium altitudes where the atmosphere is somewhat rarifled'the bellows wall or body of the aneroid is expanded and the inner head 91 of the sameis moved inwardly to some extent, thereby compressing the spring IN to a greater extent and causing the same to exert greater resistance to the opening of the valve 94 and thus require greater exhalation before this valve will open to permit the spent exhalation fluid to escape. When flying at extremely high altitudes the inner end or head of the exhalation valve stem engages with the inner head or spider 89 of the exhalation valve case which head acts as a stop to prevent the increased rariflcation of the atmosphere in these altitudes from further increasing the compression of the spring IM and the increased resistance which the same would otherwise offer to the opening of the exhalation valve 94. It has been calculated that the heads of the aneroid will remain in engagement with each other so that the aneroid will not aflect the compression of the spring IOI up to an altitude of 30,000 feet but the aneroid will operate and put this spring under increased compression and thus increase the resistanceto the opeing of the exhalation valve up to anualtitude of 45,000 feet at which time the valve stem 99 will engage the stop 89 and prevent further compression of this spring. The reason for limiting the expansion of the aneroid is that ordinarily the expansion of the aneroid is directly proportional to the elevation of the flying machine but the human breathing requirements as to the back pressure on the exhalation valve are not directly proportional to elevation in that it is not'desirable to have any material increase of back pressure on the exhalation valve above an altitude of 45,000 feet. The present organization therefore is such that at levels up to 30,000 feet the spring IOI will offer a relatively low resistance 'tothe opening of the exhalation valve, while flying atfan alti tude of 30,000 to 45,000 feet the resistance to the opening of the exhalation valve will be increased, at altitudes above 45,000 feet the aneroid is-prevented from further increasing the resistance to the opening of this valve.

It is extremely important that when the aviator is flying at an altitude of approximately 37,000 feet the oxygen supplied to himby this apparatus is not diluted with air and this is ensured in accordance with. the present invention by means which maintain the pressurein the mask always above. ambient.pressure as follows:

As shown in Figs. 3 and 5, the numeral I02 represents an aneroid lever arranged in the respiration chamber and pivoted at one of its ends by a pin I09 on a bracket I04 securedv to the inner side of the back wall 46 of the .respirationchamber, while its opposite end is yieidingly drawn toward this wall by a spring I05 which has its inner end connected with the free end of the lever I02 while its outer end is-connectcd' with a screw I016 secured in an opening in said back walL- Intermediate of its ends this aneroid lever I02 bears with its outer side against the inner movable end of an aneroid I01 which has its outer end secured to the inner side of the adjacent part of the back wall 48. This aneroid is of substantially the same-construction as that shown in Fig. 6. Expansion of this 9 aneroid is adjustably limited by stop means consisting preferably of a stop bolt I08 having its outer end secured to the wall 4-6 and its inner end arranged in an opening I09 in the free end of the aneroid lever I02, a stop screw nut IIO adjustable with an adjustable bearing point II3 which enages with the inner side of the aneroid lever I02 and preferably has the form of a screw engaging with a threaded opening in this lever. This aneroid I! is responsive to the ambient pressure at different altitudes and operates through the medium of the parts which operatively connect the same with the toggle mechanism to provide a negative minimum pressure at low altitudes in the respiration chamber and the spaces communicating therewith, and a positive minimum pressure therein at higher altitudes.

Automatic control means are provided for causing oxygen to be admitted to the respiration chamber in accordance with the altitude at which the aviator is flying which means are best shown in Figs. 1 and 4 and constructed as follows:

The numeral I I4 represents a dish-shaped cover arranged outside of the diaphragm 49 and having its edge secured around the adjacent part of the body side wall 41 by screws H5 or otherwise while the peripheral part is provided with openings 2I6 for maintaining atmospheric pressure within this cover. Within this cover is arranged an aneroid comprising a flexible corrugated or bellows body II6, an outer head I" secured to the outer end of the bellows and mounted on the central part of the inner side of the cover, and an inner head I I8 secured to the inner end of the bellows and adapted to engage the outer head of this bellows in the contracted condition of the latter, thereby forming a. hermetically sealed box or chamber from which the air has been partially exhausted. Within this box is arranged a compressed spring II9 bearing at its ends against the heads III and I I8 which assists in expanding this aneroid when the atmosphere becomes rarified in the higher altitudes instead of relying on the resilience of the bellows body II6 to push the inner head I I8 longitudinally inward against the external ambient atmospheric pressure.

The numeral I20 represents a buffer which has the form of a hollow or cup-shaped foot and is .out of engagement from the diaphragm when the latter is contracted but which in the fully expanded condition of the diaphragm is engaged by the latter and resists the final part of its expansion for the purpose of building up pressure in the respiration chamber. This buffer is preferably constructed in the form of a cup which is arranged within the cover H4 at the inner end of the aneroid therein and is provided in the center of its bottom with an opening I2I which receives the inner part of a guide post I22 projecting inwardly from the inner head H8 of the aneroid bellows H6. The numeral I23 represents a helical spring which surrounds the guide post I22 and is interposed between the buffer and the inner head of the aneroid bellows H6 and operates to yieldingly hold the buffer at a distancefrom the inner end of this aneroid. This movement of the respective aneroid-is limited by stop means consisting preferably of a washer I24 engaging the inner side of the post I22 and secured to the inher end of this post by a screw I25, as shown in Fig. 4. The spring I23 permits a certain amount of movement of the diaphragm after the disk I28 on the outer side of the same has contacted the buffer. If the spring I23 were not used a delicate adjustment of-the buffer I20 relative to the diaphragm would be necessary in order to avoid bringing the diaphragm to a sudden stop when arresting its expansion movement and as a consequence the toggle mechanism would not be actuated unless the diaphragm shifted the toggle levers into their foremost position before the diaphragm contacted this aneroid. From this it will be evident that this aneroid would beuseless unless it is permitted to perform its function 01' automatically varying the time of tripping the toggle mechanism for stoppin the flow of oxygen into the respiration chamber through its inlet 50 in accordance with the altitude at'which the aviator is'flying, that is to say, at low altitudes the aneroid II8 will contract and cause the admission of oxygen to be cut off earlier and at high altitudes'this aneroid will expand and'cause the admission of oxygen into the respiration chamber to be cut off later. v During normal breathing a person expands the diaphragm and ribs of his chest and sucks in fresh oxygen loaded air. At the end of the inhalation, when the'positive pressure in the lungs is at its maximum, a normal'person usually pauses for a moment before allowingthe' muscles of the chest to relax and thus prevent lowering of the pressure inthe lungs so rapidly as would provide insufflcient time for permitting the osmosis operation in the lungs to be effected. In accordance with the present invention the oxygen is forced positively into the aviators lungs but when the pressure reaches a predetermined maxi mum it is not allowed to fall too rapidly. This is accomplished by a retarding valve mechanism which prevents the pressure of the-fluid in the respiration compartment, the mask and the hose connecting the same, upon reaching its maximum, from dropping too rapidly and thus allow ample time for the lungs of the person using the apparatus to perform their osmotic function of absorbing adequate oxygen. The. preferred form of this retarding valve mechanism is shown in Figs. 3, 4 and 6 and is constructed as follows:

The numeral I21 represents a retarding valve case which is secured by the screws 93 to the outer side of the mask inline with the exhalation valve mechanism and which contains a' 88 through the openings 92 and the-front chamber I30 is in constant communication with the outer atmosphere through an opening I32. Within the inner chamber I29 is arranged a control or retarding valve I33, preferably of disk form' which is movable lengthwise toward and from the valve port- I3I for the purpose of covering and uncovering the same more or less and thus varying the rapidity of flow of the spent fluid from exhalation valve mechanism to the atmosphere. Theretarding valve In is adlustably mounted on a longitudinally movable valve stem I34 which slides in a guide opening in the partition and provided with a thread on its inner part which engages a threaded opening in the center of the valve I". After adjusting the retarding valve into the desired position on the stem it is held in place by a clamping screw nut. I" on the inner part of this stem and engaging the inner side of this valve, as shown in Fig. 6. At its outer or front end the valve stem I34 is connected with a head I38 on the inner end of a diaphragm I31 which is preferably of bellows form and has its outer end securedto the outer wall or head In of the chamber I30. Collapsing of the bellows diaphragm I31 is eil'ected by a spring I which is interposed between the partition' I28 and the inner head I32 and tends constantly to push the latter outwardly.

Within the respiration chamber is arranged an auxiliary valve mechanism which. controls the spent fluid retardingmechanism and which operates in harmony with the toggle mechanism whereby admission 'of oxygen to the apparatus .;is

controlled. This auxiliary valve mechanism in its preferred form is constructed as follows andshown inFifgs;"3,4 ',and-6:- s .On the rear wall- 46 of the respiration chamber.

--is mounted the'casing of the auxiliary valve mechanism-whichlpreferably comprises a longitudinal body I40 containing an auxiliary valve chamber I4I whichis provided at'its lower and upper ends withhea'ds'lfl, I43. The'lower part 5 of the valve chamber .I4I communicates constant- 1y with the fluid inlet valve chamber 52 below or in advanceoi the main tilt valve 5! by means of an inlet or tube I44. The upper, head I4! is provided on its inner end with a port I which I head I42 and has its outer end overlying a cantilever arm II! of angular form which is connected with the arm 63 oi the lower toggle lever and proiects from the opposite side of the axis 64, as shown in Fig. 3. Whenever the toggle mechanism operates to open the main oxygen inlet valve 58 then the cantilever arm II! moves the valve stem from its central normal position, in which the valve I49is closed, to a tilted position in which this valve is opened. This valve is yield- Ingly held in its closed position by a spring I" interposed between the stem of this valve and the casing head I42 on which this stem rocks so that this spring is deflected when this valve is opened by the rearward folding action of the toggle mechanism andthe forward throw of the cantilever arm I52 but when the latter is moved rearwardly during the forward folding action of the toggle in'its closed position by, a spring I51 interposed the helical form of the'tube I 46 causes the same her I is'provided withan annular row of ports or openings I41 and a rearwardly facing valve I between the sameandajshou'lder l'll on the inner 'side'of the casing body I40 and thisvalve is guided in its movements toward and from: its

valve seat I54 by a guide stem I50 secured at one end to this spring I" and sliding at its opposite end in an opening I60 in the upper casing-head I43, as shown in Fig. 8. I

As the aviator exhales 'the'control valve In opens slowly, but closes rapidly when he inhales so as to prevent the higher than ambient pressure which is being built up-in the mask from escaplng through the loaded exhalation valve 94. This result is due to the opening of the main tilt valve 58 and the auxiliary tilt valve I48 whereby the pressure previously stored in the mask bellows I31 quickly passes out through the flexible tube I46 and past the check valve I into the auxiliary valve chamber I ,and through the open auxiliary tilt valve I49 into the main respiration chamber 48. It is true that. at this time, oxygen under pressure is being fed into thev respiration chamber through the open main tilt valve 58, but this is immaterial because it takes some time for this pressure to build up in the'respiration chamber and the pressure in the seat I48 on the inner side'of thishead around these ports. These ports are covered and uncovered by an auxiliary tiltable oxygen inlet valve I48 arranged within the lower part of the auxiliary chamber-HI and adapted to either engage the valve seat I48 over its entire area, as shown in Fig. 3, and thus close'the ports I41 and prevent the passage' ofoxygen. or fluid from-the respirationfchamberLinto the transfer chamber, or to engage-only part of this valve seat tilting relativeto the sameand thus uncoverthese ports and permitoxygen to flow fromthe letter at no time even remotely approaches the pressure at the main gas inlet 52 before it is reduced to permit of its use" in this apparatus. Moreover the main inlet valve "is closed before a very high pressure can be built .up in the respiration compartment-48,. I

' The relatively'high fluid pressure in the inlet -52 oi'the apparatus is utilized, upon opening the main valve ",to' expand'the bellows I" on the mask due to" the i'ollowingiaction:

' Upon commencing an exhalation'the tiltvalves 58 and I43 are both closed by the toggle mechanism and oxygen. at relatively high pressure is respiration chamber '48 into the auxiliary chamber m. Opening or the auxiliary valve In is eil'ected by motion derived from the toggle mech- 'anism .and closing .of the same is eifectedby spring return means. For this purpose the auxiliary valve is connected with theinner end oi a valve stem I50 which is adapted t0 N P it conducted from the high pressure inlet 52 through the tube I44 into the auxiliary valve compartment I4I. As'the auxiliary tilt valve I4! isclosed during this exhalation period and-the metal check valve I55 is also closed, it is only possible for this relatively high pressure oxygen to flow slowly through the leak opening I56 in this check valve I55 and pass through the upper flexible tube I48 13 into the bellows I31 and inflate the latter. This inflation is relatively slow due to the resistance to backward flow of oxygen through the check valve and the friction and capillary action of the tubes I48 and I44 which are of relatively small internal diameters. This results in the control valve I33 opening slowly at the beginning of the exhalation period and then preventing the lungs from too rapidly discharging the spent fluid which they had just received during the previous inhalation period.

In accordance with this-operation of the apparatus oxygen will be forced into the lungs of the aviator from ground level up to an altitude of 25,000 feet which forcing after it has commenced is fully automatic, except that the aviator can exhale whenever he desires to do so, but when exhaling he must first get the pressure in the mask up to the normal maximum inhalation pressure before the spent air can be vented from the mask. At this range of elevation and up to an altitude of 30,000 feet the aviator has complete control of the beginning of the inhalation period because a negative pressure is required to flip the toggle mechanism and the valves operated thereby into an open position.

At higher elevations the matter of leakage of air into the mask becomes vital and hence the instrument, because of the use of the aneroid I01 and associated mechanism, requires a small minimum positive pressure to start the inhalation period. This means that the pressure in the mask is always positive at these higher elevations and any leakage of the mask can only be outward and not inward. Concomitantly the instrument becomes automatic to the extent that if the aviator "blacks out" the instrument will effect automatic breathing for the aviator. Nevertheless, if the aviator is conscious, he has considerable control over the beginning of his inhalation and exhalation cycles, but he is incapable of changing the maximum and minimum pressures, which minimum positive pressure cannot be increased above an altitude of 37,000 feet due to stop nut IIO which limits the expansion of the aneroid I01 at high altitudes.

At all elevations the control valve I33 so operates that the aviators lungs are subjected to substantially maximum pressure for an appreciable length of time after the beginning of each exhalation period so that a reasonable length-of time is afforded for the osmotic exchange in the lungs of oxygen and carbon dioxide. To compensate for the lower ambient pressure at high elevations both the maximum pressures are raised, the aneroid I I6 operating to raise the maximum pressure during inhalation and the aneroid raising the pressure during exhalation, but at an elevation of 45,000 feet further movement of the aneroid 98 is prevented by its head I striking the inner face of the spider or wall 89.

It will be apparent that in using this apparatus the aviator has almost complete control of his breathing cycles. 0n inhalation however he cannot prevent the building up of pressure but he can start exhaling any time he desires and due to a negative pressure being required before the main oxygen valve 58 will open it is evident that the apparatus is not automatic as to starting the inhalation period. This therefore operates to prevent over ventilation as previously explained.

From the foregoing it will be apparent that by the use of the exhalation valve 94 which is subject to the influence of the aneroid 93 responsive to altitude, and the control valve I33 which is subject to the action of the bellows I31 by pressure derived from the main pressure source that the control valve will be closed slowly at the start of the exhalation cycle and that the control valve will be closed instantly by means of the spring I39 when the pressure in the bellows I31 drops below normal, thereby preventing gas from leaking outwardly past the exhalation valve 94 even. though the pressure in the mask becomes higher than that which would open the exhalation valve if the control valve were absent.

Inasmuch as the exhalation valve 94 is arranged close to lthe aviators face the warmth of the latter prevents this valve from freezing and becoming inoperative but this is not liable to occur to the control valve I33, notwithstanding the same is exposed to a greater extent to the atmosphere because the means for actuating the same by power derived from the pressure in the main or respiration chamber are sufliciently powerfulto overcome the effects of frost or low temperature.

It is to be noted that owing to the location of the inhalation valve 94 and associated parts on the inside of the mask the same are not likely to become inoperative due to freezing when the aviator is flying at extremely high altitudes.

From the foregoing it will be apparent that this breathing apparatus will operate wholly automatically for supplying oxygen to a person who is unconscious and unable to aid himself and will also cooperate with a person who is sufflciently conscious to assist this apparatus in supplying oxygen, I

The sequence of the several steps in the complete operation of the breathing apparatus shown in Figs. 1-7 and indicated on the charts or graphs shown in Figs. 8, 9 and 10 as follows:

Pure oxygen is supplied at high pressure, say 1,000 pounds per square inch, from a suitable tank, bottle, or elsewhere and fed to the inlet 2I of the pressure regulator which reduces the pressure of the oxygen to say 40 pounds per square inch and delivers the same at this pressure to the inlet side 52 of the valve 58 which controls the flow of the fluid through the inlet 50 into the respiration chamber 48 of the automatic control mechanism. The control valve 58 is opened by the toggle actuating mechanism during the last part of the rearward or contracting movement of the diaphragm 49 and closed during the last part of the forward or expanding movement of the same. The screw I2 permits of effecting a fine adjustment of the maximum pressure which may be built up in the respiration chamber 48 before the admission of further oxygen into this chamber is cut off. From the respiration chamber the oxygen passes through the outlet 6| thereof into the corrugated tube 83 and delivered by the latter into the face mask where it is inhaled by the aviator. Upon exhalation of the aviator the spent fluid is discharged past the exhalation valve 94 to the outer atmosphere. Owing to the large size of the hose or tube 83 the pressure within the respiration chamber and within the face mask is always substantially the same.

Let it be assumed that the aviator has previously received and inhaled oxygen under pressure and is now exhaling foul air into the mask from which it flows past the loaded exhalation check valve 94 and past the retarding valve I33 to the outer atmosphere. As he continues to exhale, and, concomitantly the volume of air in his lungs becomes increasingly depleted and consequently 15 the lung actuating muscles become relaxed, the pressure in the face mask and in the respiration compartment 48 will drop comparatively rapidly, as indicated by the curve a on the graph Fig. 8 from the high level b and level oil to a small positive pressure 0. At ground level and up to an altitude of 30,000 feet, this small positive pressure at b persists indefinitely until the aviator starts to inhale again, thereby preventing the aviator from getting more oxygen than he needs, in other words, it prevents what is commonly termed over-ventilation." By maintaining this negative pressure at this time he is prevented from being inflated until he inhales and then only gets a "shot of oxygen when he wants it, this being caused by the negative pressure resulting from his inhalation. This inhalation drops the presthat at the time the oxygen inlet valves 48, I49

sure in the mask and in the respiration compartment 4! to a point below the ambient air pressure which prevails in the airplane cabin at that particular moment and at that particular elevation. In other words, it is the negative pressure,.

point d, caused by the inhalation of the aviator, which produces the higher ambient pressure on the outside of the diaphragm for pushing the latter inwardly and to thereby fold the togB e levers rearwardly so that the toggle levers are moved rearwardly past the dead center 64 and the main oxygen inlet valve 58 is opened. Upon tilting this main valve 58 into an open position, the auxiliary oxygen inlet valve I49 is also tilted into an open position so that oxygen for subsequent inhalationis simultaneously admitted by these two valves into the respiration chamber. After these two valves 58, I4! have been snapped'into their open or inhalation positionsthe diaphragm continues to collapse until its leg l1 strikes the back wall 48 of the casin Neither the extent of inward movement of the diaphragm and its leg 11, nor the consequent backward folding action of the toggle levers are of themselves important after the main and auxiliary oxygen inlet valves 50, I49 have been opened, but the diaphragm is immediately subjected to increasing pressure on its inner side by the incoming oxygen under pressure and the toggle levers are immediately subjected to an increasing pressure tending to move them outwardly to and past the dead center 64 into an outwardly folded position and again close the main and auxiliary oxygen inlet valves. With the inner end of the diaphragm leg 11 in contact with the casing back it will be obvious that the position of the lower toggle lever 62, 63, 61 will determine the leverage exerted by the diaphragm upon the upper toggle lever SI, 69, I0 and the tensionof the 'toggle'spring 'II and the effect of the latter in opposing the outward or expanding movement of the diaphragm. The inward or rearward movement of the main toggle levers is controlled by the adjustable stop screw I2 thereby determining how high the pressure in the respiration chamber 48 and the mask will go before the diaphragm trips the toggle mechanism and closes the main and auxiliary oxygen inlet valves 58, I49.

-Upon inhalation, while oxygen is forced into the aviators lungs under pressure, and while the aviatoris flying up to an altitude of 25,000 feet the rising pressure curve is represented at e in graph Fig. 8 while b indicates the point at which the toggle mechanism operates the valves 58, I49 to cut off the supply of oxygen to the respiration chamber.

It is to be understood that if the pressure on 16' line c rises to point I which is below b, and if at this point of pressure f the aviator starts to exhale, this action will cause the pressure-in the mask to first rise to point a, and then the toggle mechanism will -be tripped and cut off the supply of oxygen. Thus the aviator has almost complete control of his breathing cycle. On inhalation he cannot prevent building up of pressure in the mask and respiration chamber but he can start exhaling any time he desires and the fact that a negative pressure is required at d before the main oxygen valve 58 is opened shows that the apparatus is not automatic as to the starting of the inhalation cycle, and thus prevents "overventilation as previously explained. This negative pressure from ground level up to an altitude of 30,000 feet is due to so adjusting the spring are open this spring 80 is not under tension and does not exert any pressure whatsoever and therefore is unable to move the toggle mechanism for shutting off the supply of oxygen. The pressure to effect closing of the oxygen inlet valves 58, I49 is due to the negative pressure caused by the aviator starting to inhale at point h as indicated in Fig. 8. The toggle spring 'II becomes active as the diaphragm moves outwardly so that the toggle mechanism closes the oxygen inlet valves and places the spring 80 under tension preparatory to assisting in again opening the oxygen inlet valves.

Up to an altitude of 30,000feetthe minimum pressure is controlled by the adjusting screw I4 which limits the movement of the toggle mechanism in the direction for closing the main and auxiliary oxygen inlet valves. It will be obvious that when the diaphragm is in its outward or expanded position the toggle spring II is in its most effective position to resist the inward contracting movement of the diaphragm and folding movement of the toggle levers. It therefore follows that this screw determines how low the pressure in the respiration chamber and mask can drop before the diaphragm can snap the toggle mechanism for moving the oxygen inlet valves into an open position, which inthe present case is assumed to occur at an elevation of 30,000 feet.

It is true that the more the toggle levers are folded the weaker becomes the spring II but this is more than offeset by the increased power of this spring when these levers are folded to a greater extent.

When the aviator reaches an altitude above 30,000 feet the aneroid I01 has expanded to such an extent that the lever I02 is-pushed outwardly into contact with the adjusting screw II3 while the toggle mechanism is in a position in which the oxygen inlet valves are in their closed position. This causes the cantilever II2 of the toggle mechanism to be lifted off of the minimum pressure adjusting screw 12 and thus raises the minimum pressure from point i to point as indicated on the graph Fig. 9, upon reaching an altitude of 37,000 feet. Dilution of the oxygen with air at such an elevation istherefore prevented and ensures having the pressure in the mask always above ambient pressure-and thus prevent outside air from possibly leaking into the mask. Due to this positive minimum pressure the apparatus becomes completely automatic at an altitude of 30,000 feet so that if the aviator becomes unconscious and his lungs continue to collapse until the pressure in the mask drops to point a on the graph Fig. 9, which is the same as the minimum The aneroid II5 engages the diaphragm disk I 25 at an elevation of about 25,000 feet. At low altitudes and up to about this elevation the aneroid II5 is in a collapsed condition due to the ambient pressures at these levels, the collapsing of this aneroid being limited by engagement of its and heads, as shown in Fig. 4. At anelevation of 25,000 feet the ambient pressure has dropped sufllciently to cause this aneroid to expand and engage its buffer I20 with the bearing disk I26 on the outer side of the diaphragm so that greater pressure must be built up in the respiration chamber before the toggle mechanism is tripped by the inward movement of the diaphragm and stops the flow of oxygen into the respiration chamber.

In other words, the point b of the 25,000 foot curve shown on graph Fig. 8 is raised to point It upon reaching an altitude of 37,000 feet, as shown in graph Fig. 9. As the aviator reaches still higher altitudes, the curve of the. ambient pressure increases relatively and at, say 50,000 feet altitude, the point on the curve corresponding to the altitude would reach point 1 shown in graph Fig. 10.

It is desirable, as previously explained, to have the points :7, above the zero or ambient line, as indicated in Fig. 9. Inasmuch, however, as too great a minimum positive pressure may cause excessive exertion on the part of the aviator during exhalation the outward movement of the aneroid lever II 2 is limited by means of the adjustable stop screw nut IIO whereby this pressure is arrested at point m, as indicated in Fig. 10.

As the aviator ascends and the ambient pressure decreases the effective force of the compression spring 99 is increased by the aneroid 95, the heads 96, 91 of which remain in engagement with each other up to an altitude of 30,000 feet but separate thereafter so as to put increasing pressure on this spring until the aviator'gets up to 45,000 feet, at which time the head I of the retainin screw 99 engages the spider 59 of the casing of this valve 94 and thus prevents the aneroid 90 from putting more pressure on the exhalation valve 94. Above an altitude of 45,000 feet resistance to the opening of the exhalation valve 94 should increase and this extra resilience is obtained by the present means which are compact and do not require an undue amount of space in the apparatus.

As the aviator breathes rapid inhaling is possible but too rapid falling of the pressure in the mask is prevented in order to obtain the necessary osmotic action by the operation of the retarding valve I33, the position of which is controlled by the operation of the bellows I31, the metal check valve I05 and the auxiliary oxygen supply valve I49, as previously explained. As a. result of the operation of this control mechanism the pressure curves do not drop sharply from the points bkl but continue in a more or less level fashion to points nop before falling off, as shown in Figs. 8, 9 and 10.

To compensate for the lower ambient pressure at relatively high elevations all the maximum pressure points bkl are raised due to the operation of the aneroid H5, and the exhalation pressure points car are raised by the operation of the aneroid 98, but at extremely high altitudes, say, 45,000 feet, further expansion movement of the aneroid 95 is prevented by the head I00 striking the spider 59.

It is to be noted in this connection that the leakage through the metered hole I55 in the check valve I55 must be sufficient to allow the required flow of oxygen from the auxiliary valvechamber I through the capillary tube I to the bellows I31. The apparatus is therefore tested for different sizes of holes I55 until the exact diameter is obtained which gives the desired results and then this diameter is maintained within close tolerances, so that in eifect this orifice I55 is adjustable but has a fixed setting after the required size has been determined.

In the preferred organization of this apparatus the opening of the auxiliary oxygen inlet valve I49 and the opening of the main oxygen inlet valve 58 are so timed that the opening of these valves occurs at the same time, as shown in Fig. 4. and the closing of the same is effected in like manner. This allows the auxiliary valve chamber III to have the same low pressure as the respiration chamber 45 and hence allows the control spring I39 of the mask to collapse the bellows I31 and force its contents past the check valve I55 and out into the diaphragm chamber 40. However,\yvhen the person starts to exhale, he raises the pressure in this respiration chamber 45, forces the diaphragm out, and causes the toggles to fold outwardly, thus closing both the main and auxiliary tilt valves 58 and I49. The closing of the auxiliary tilt valve I49 causes the relatively high pressure oxygen in the capillary tube I44 to fill the auxiliary valve chamber Hi. This pressure will pass through the metered hole I55 and expand the bellows I 31 in the mask against the resistance of its compression spring I39 and thus open the control valve I33 to its fully open position to permit of free exhalation. The metered hole I55, however, restrains this movement at the start of the exhalation, so that the aviator is prevented from exhaling freely until a certain interval of time has elapsed. In other words, the lungs are kept inflated for a longer period of time than would be the case if the orifice I55 were larger and the bores of the flexible tubes I44 and I45 larger. This means that the crests of all of the waves of Figs. 8, 9 and 10 are caused to be relatively wide (flattened) at their tops, instead of having sharp points. It will be clear now that the mechanism which includes the auxiliary oxygen inlet valve I49, the control valve I33 and the tubes I44 and I45 connecting the auxiliary inlet chamber III with the main oxygen supply chamber 52 and the bellows I31, respectively, will cause this apparatus to so function that when a person has inhaled as much of the air, or oxygen, or airoxygen mix as he desires he will be prevented from starting to exhale at too rapid a rate, be-

a cause it takes a certain length of time for the the main oxygen inlet valve 58 and the auxiliary oxygen inlet valve are operatively connected with the diaphragm through the medium of the toggle mechanism and associated parts, it is to be understood that any other suitable means may be employed for more directly transmitting the movement of this diaphragm to said valves for actuating them relative to the other parts with which they are associated in accordance with this invention.

The breathing apparatus shown in Figs. 11-17 is an organization which embodies this invention in asimplifled form for use at ground level or low altitude by persons who may be either conscious or unconscious for therapeutic treatment of pulmonary edema which is caused by war gases or like ailments. Victims of war gases are usually require an aneroid similar to the aneroid I01 and associated mechanism to change the minimum in the apparatus from negative to positive, nor are any of the other aneroid mechanisms required which cause the apparatus to function properly at diilerent altitudes. In actual practice the apparatus shown in Figs. 11-17 ordinarily functions on a negative minimum pressure on patients who are conscious and exerts a negative pressure similar to the curve indicated on the graph or chart Fig. 12 for an altitude up to 25,000 feet before he will be inflated with oxygen by positive pressure. If desired the apparatus shown in Figs. 11-17 may be set to take care of unconscious persons in the manner indicated by the graph in Fig. 13.

In these figures no mechanism is employed outside of the diaphragm for increasing the expanding action of the diaphragm. The construction and operation of the toggle mechanism and the means for actuatng the main oxygen inlet valve 50 are the same as those shown in Figs. 3, 4 and 7, with the following exception, and the same description and reference characters, so far as they apply, will not be repeated. Instead of employing the screw 82 shown in Fig. 4 for adjusting the tension of the spring 80, this is accomplished in the construction shown in Figs. 14, 15 and 16 by a cantilever spring arm 200 of angular form which has its low fixed end secured to the back wall 46 of the respiration chamber 48 by a bolt 20l while its elevated free end is connected with the inner or front end of the tension spring 202, and an adjusting screw 203 which turns in the back wall 46 and bears with its head against the outside of the latter while the threaded inner end of this screw engages with a threaded opening in the spring arm 200 between the ends there- 01. By turning the screw 203 the spring 202 may be adjusted so that the same is under no tension when the parts are in a position if an inhalation cycle is to be started by a negative or suction pressure on the part of the patient under treatment.

Instead of arranging the exhalation valve and its aneroid mechanism on the inner side of the mask, as shown in Fig 6, this valve and its aneroid mechanism may be arranged outside of the mask, as shown in Fig. 17. In this last mentioned figure the exhalation valve 200 is movable toward and from a seat 205 on the front side of the housing 205 which encloses the aneroid I31 associated with the valve I23. The exhalation valve 200 surrounds ports 201 in the outer wall 208 of the chamber I30 and is guided in its movements by a guide pin 209 secured to the wall 200 and passing through a guide hole in the cennot unconscious. hence the apparatus does not ter of the valve 204. The latter is yieldlngiy held in engagement with the seat 205 by a spring 2i0 surrounding this guide pin and bearing with its opposite ends against the outer side of this valve and an adjustable screw nut 21! working on the threaded outer end of the pin 209. Upon turning the screw nut 2| l the resistance of the spring M0 to the opening of the valve 204 when subjected to the exhalation pressure of the patient may be regulated.

In the construction of the retarding mechanism shown in Fig. 14 no check valve device is utilized between the interior of the valve chamber HI and the lower end of the conduit I" such as is employed in the construction shown in Fig. 3.

The operation of the apparatus shown in Figs. 11-17 operates in substantially the same manner as that shown in Figs. 1-10. The fluid which it feeds to a person is however not confined to oxygen and in its stead any other gaseous fluid maybe administered by the same to a person, such as carbon dioxde or medicated air, to suit the therapeutic requirements of the person being treated.

Inasmuch as the instrument shown in Figs. 11- 17 is intended for use in hospitals, at ground level and lower altitudes, the graphs shown in Figs. 12 and 13 and indica ing the operation of the same are confined to these levels and as the same correspond to the graphs shown in Figs. 8 and 9 relating to the operation at ground level or lower altitudes of the instrument shown in Figs. 1-7, the same description and identifying characters refer to both forms of this invention so far as they apply.

When the check valve I55, shown in Fig. 3, is omitted from the auxiliary valve chamber HI, as shown in-Fig. 14, the flexble tube I46 is made sufficiently small in diameter so that the flo of oxygen through the same into the bellows I3! is sufficiently retarded by the frictional resistance within this tube to effect too rapid opening of the control valve I33.

It will be noted that in Figs. 14, 15, and 16 the pin 8| and the lug I02 are reversed on the upper and lower toggle levers of the toggle mechanism as compared with the showing in Figs. 3, 4 and 7, to suit the changed location of the parts with which they cooperate without however changing the function of the same.

I claim as my invention.

1. A breathing apparatus comprising. a respiration chamber having an inlet adapted to be connected with a supply of oxygen under pressure and an outlet adapted to be connected with the breathing system of a person, valve means for opening and closing said inlet, and control means for controlling the opening of said valve means for increasing the maximum pressure at which the lungs of said person are inflated in proportion to the altitude where the apparatus is used including a, diaphragm which is operatively associated with said valve means, an aneroid device which is inactive relative to said diaphragm in lower altitudes but operates in higher altitudes to resist the expansion of said diaphragm, and yielding buffer means interposed between said diaphragm and said aneroid device.

2. A breathing apparatus comprising a respiration chamber having an inlet adapted to be connected with a supply of oxygen under pressure and an outlet adapted to be connected with the breathing system of a person, valve means for opening and closing said inlet, and control means 21 for controlling the opening of said valve means for increasing the maximum pressure at which the lungs oi. said person are inflated in proportion to the altitude where the apparatus is used including a diaphragm which is expanded by pressure of oxygen in said chamber, means operatively connecting said diaphragm and inlet valve means including a toggle snap action mechanism, and an aneroid device which includes a bellows body, a relatively stationary head connected with one end of said body, a'movable head connected with the opposite end or said body,.and yielding buffer means adapted to be interposed between said diaphragm and said movable head and including a guide arranged on said movable head, a bufier slidable on said guide and adapted to be engaged by said diaphragm, and a spring interposed between said buffer and movable head.

3. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under compression and an outlet, a mask communicating with said outlet and having an exhalation passage, main valve means controlling said inlet, and auxiliary valve means for controlling said exhalation passage including a movable control valve adapted to control said exhalation passage, an auxiliary chamber having an auxiliary port leading to said respiration chamber, an auxiliary valve controlling said auxiliary port, pressure responsive means communicating with said auxiliary chamber and actuating said control valve, and actuating means responsive to rising and falling pressure in said respiration chamber and operativeiy connected with said mafn and auxiliary valves for opening the same when the pressure in said respiration chamber rises to a pre- 4 determined point.

4. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under compression and an outlet, a mask communicating with said outlet and having an exhalation passage, main valve means controlling said inlet, and auxiliary valve means for controlling said exhalation passage including movable control valve adapted to control said exhalation rawsage, an auxiliary chamber having an auxiliary port leading to said respiration chamber, an auxiliary valve controlling said auxiliary port, pressure responsive means communicating with said auxii.

iary chamber and actuating said control valve.

and actuating means responsive to rising and falling pressure in said respiration chamber and operatively connected with said main and auxiliary valves for opening the same when the pressure in said respiration chamber rises to a predetermined point and said actuating means being timed to open sa.'d auxiliary valve in advance of the opening of said main valve.

5. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under compression and an outlet, a mask communicating with said outlet and having an exhalation passage, main valve means controlling said inlet, and auxiliary valve means for controlling said exhalation passage including a movable control valve adapted to control said exhalation passage, an auxiliary chamber having an auxiliary port leading to said respiration chamber, an auxiliary valve controlling said auxiliary port, pressure responsive means communicating with said auxiliary vhamber and actuating said control valve, actuating means responsive to rising and falling pressure insaid respiration chamber and operatively connected with said main and auxiliary point, and a conduit which places said auxiliary chamber in communication with said oxygen supply source in advance of said main inlet valve.

6. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under compression and an outlet, a mask communicating with said outlet and having an exhalation passage, main valve means controlling said inlet, and auxiliary valve means for controlling said exhalation passage, including a movable control valve adapted to control said exhalation passage,

an auxiliary chamber having an auxiliary port leading to said respiration chamber, an auxiliary valve controlling said auxiliary port, pressure responsive means communicating with said auxiliary chamber and actuating said control valve, actuating means responsive to rising and falling pressure in said respiration chamber and operatively connected with said main and auxiliary valves for opening the same when the pressure in said respiration chamber rises to a predetermined paint, and a check valve arranged in the line of communication between said auxiliary chamber and said exhalation passage and opening toward said auxiliary valve.

7. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under compression and an outlet, a mask communcating with said outlet and having an exhalation passage, main valve means controlling said inlet, and auxiliary valve means for controlling said exhalation passage including a movable control valve adapted to control said exhalation passage, an auxiliary chamber having an auxiliary port leading to said respiration chamber, an auxiliary valve controlling said auxiliary port, pressure responsive means communicating with said auxiliary char-her and actuating said control valve, actuating means responsive to rising and falling pressure in said respiration chamber and operatively connected with said main and auxiliary valves for opening the same when the pressure in said respiratlon chamber rises to a predetermined point, and a check valve arranged in the line of communication between said auxiliary chamber and said exhalation passage and opening toward said auxiliary valve and said check valve having a metered orifice.

8. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under compression andan outlet, a mask communicating with said outlet and having an exhalation passage, main valve means controlling said inlet, and auxiliary valve means for controlling said exhalation passage including a movable control valve adapted to control said exhalation passage,

an auxiliary chamber having an auxiliary port leading to said respiration chamber, an auxiliary valve controlling said auxiliary port, pressure responsive means communicating with said aux'iiary chamber and actuating said control valve. actuating means responsive to rising and falling pressure in said respiration chamber and operativeiy connected with said main and auxiliary valves for opening the same when the pressure in said respiration chamber rises to a predetermined point, and means for actuating said control valve including a bellows which is connected with said control valve and the interior of which communicates with said auxiliary chamber.

9. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under pressure and an outlet for oxygen, a main valve for controlling said inlet, a mask having a discharge passage ior spent gas leading to the outer atmosphere, a conduit connecting said respiration chamber and mask, a control valve which controls said discharge passage, a bellows connected with said control valve, an auxiliary valve chamber adapted to be connected with and disconnected from said respiration chamber, and a tube connecting the interior of said auxiliary valve chamber with the interior of said bellows and having its major part arranged in said conduit and thereby preventing the same from being frozen.

10. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under pressure and an outlet for delivering o ygen to a person, an inlet valve for controlling said inlet. a diaphragm responsive to the rise and fall of pressure in said chamber, motion transmittin means for causing said valve to open when said diaphragm is collapsed and to close said valve when the diaphragm is expanded including a toggle mechanism having two levers, the main one of which is operatively associated with said valve and the other operatively associated with said diaphragm, screw adjusting means for controlling the action of the main lever of said toggle mechanism for closing said valve, and screw adjusting means for controlling the action of the main lever 01 said toggle mechanism for opening said valve.

11. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under pressure and an outlet for delivering oxygen to a person, an inlet valve for controlling said inlet, a diaphragm responsive to the rise and fall of pressure in said chamber, motion transmitting means for causing said valve to open when said diaphrgm is collapsed and to close said valve when the diaphragm is expanded including atoggle mechanism having two levers, the main one of which is operatively associated with said valve and the other operatively associated with said' diaphragm, and an aneroid mechanism for controlling the operation of said valve including a control lever which is engaged by the main lever of said toggle mechanism, an aneroid engaging said control lever and adapted to reduce the closing of said valve in higher altitudes, and adjustable means for limiting the movement of the control lever under the action of said aneroid.

12. A breathing apparatus comprising a respiration chamber having an inlet for oxygen under pressure and an outlet for delivering oxygen to a person, an inlet valve for controlling said inlet, a diaphragm responsive to the rise and fall of pressure in said chamber, motion transmitting means for causing said valve to open when said diaphragm is collapsed and to close said valve when the diaphragm is expanded including a toggle mechanism having two levers, the main one of which is operatively associated with said valve and the other operatively associated with said diaphragm, and an aneroid mechanism for controlling the operation of said valve including a control lever which is engaged by the main lever ration chamber having a valve controlled inlet for oxygen under pressure, a mask communicating with said chamber and having an exhalation passage leading to the outer atmosphere and a valve seat associated with said passage, an exhalation valve movable relative to said seat for opening and closing said passage, an aneroid device which is responsive to altitude and which operates to increase the resistance to the opening of said exhalation valve in proportion to the increase in altitude where the apparatus is used, a main inlet valve for controlling said inlet, a main outlet valve for controlling said exhalation passage, and a diaphragm which is responsive to variations in pressure in said respiration chamber and which is operatively associated with both said main inlet valve and said main outlet valve and actuates said main inlet and outlet valves in of said toggle mechanism, an aneroid engaging unison independently of said aneroid operated exhalation valve.

14. A breathing apparatus comprising a respiration chamber having a valve controlled inlet for oxygen under pressure, a mask communicating with said chamber and having an exhalation passage leading to the outer atmosphere and a valve seat associated with said passage, an exhalation valve movable relative to said seat for opening and closing said passage, an aneroid device which is responsive to altitude and which operates to increase the resistance to the opening of said exhalation valve in proportion to the increase in altitude where the apparatus is used and which is provided with means for rendering said aneroid device ineflective below a predetermined altitude, a main inlet valve for controlling said inlet, a main outlet valve for controlling said exhalation passage, and a diaphragm which is responsiv to variations in pressure in said respiration chamber and which is operatively associatcd with both said main inlet valve and said main outlet valve and actuates said main inlet and outlet valves in unison independently of said aneroid operated exhalation valve.

15. A breathing apparatus comprising a respiration chamber having a valve controlled inlet for oxygen under pressure, a mask communicating with said chamber and having an exhalation passage leading to the outer atmosphere and a valve seat associated with said passage, an exhalation valve movable relative to said seat for opening and closing said passage, an aneroid which is arranged axially in line with said exhalation valve and which expands and contracts in accordance with the altitude in which the an: paratus is located, means whereby said valve is yieldingly mounted on said aneroid and 'moved toward and from said seat, a main inlet valve for controlling said inlet, a main outlet valve for controlling said exhalation passage, and a diaphragm which is responsive to variations in pressure, in said respiration chamber and which is operatively associated with both said main inlet valve and said main outlet valve and actuates said main inlet and outlet valves in unison independently of said aneroid operated exhalation valve.

16. A breathing apparatus comprising a respiration chamber having a valve controlled inlet for oxygen under pressure, a mask communicating with said chamber and having an exhalation passage leading to the outer atmosphere and a valve seat associated with said passage, an exhalation valve movable relative to said seat for opening and closing said passage. an aneroid 

